gzip GZIP is a file archiving and compression tool associated with the .gz filename extension. The utility was first released in 1992 for the UNIX operating system, with the intention of replacing the 'compress' tool that comes bundled with UNIX. Today (2015) the tool exists as a standalone cross platform file archiver. Several archiving and compression utilities exist that support the .gz (otherwise known as gzip) format. The motivation behind the format and utility was to create a capable compression archiving tool that was unencumbered by patents of other compression algorithms that existed at the time, particularly those surrounding the LZW algorithm.
tar The .tar filename was originally designed to be used as a TApe ARchiver to store entire file systems and files as single files on tape storage medium. It was designed by AT&T in 1979. Today, the format more commonly refers to an archive or collation of multiple files into a single file with the .tar filename extension. The format is an open source file archive format commonly associated with the UNIX tar command however other data compression tools are capable of effectively compressing and/or decompressing files saved with the .tar file format. Doing so typically adds the compression filename extension to the archive file for example .tar.bz2.